Roller leveler and method for operating same

ABSTRACT

The invention relates to a roller leveler ( 1 ) having a set of upper and lower flattening rollers ( 2 ), wherein each flattening roller ( 2 ) is provided with a rotary drive ( 3 ) actuated by leveler control ( 4 ) for rotating the flattening roller ( 2 ) to advance a to-be-flattened metallic flat material in a forward direction (F) and, thereby, flatten the flat, metallic material. To achieve an improved and optimal flattening result, the invention proposes that each flattening roller ( 2 ) has a first rotary drive (L 1 , L 2  . . . L n ) for driving one axial end of the flattening roller ( 2 ), and a second rotary drive (R 1 , R 2  . . . R n ) for driving one axial end of the flattening roller ( 2 ) and a second rotary drive (R 1 , R 2  . . . R n ) for driving the other end of the flattening roller, wherein the leveler controller ( 4 ) is designed to apply a parameter determining the direction of rotation of the flattening roller ( 2 ) to the first and second rotary drives (L 1 , L 2  . . . L n , R 1 , R 2  . . . R n ) individually based on a pre-set value. The invention also relates to a method of operating a roller leveler of this kind.

The present invention relates to a roller leveler having a set of upper and lower flatteningrollers, with each flatteningroller being provided with a rotary drive actuated by a leveler control for rotating the flatteningroller in order to advance a to-be-flattening flat material in a conveying direction to thereby flattening the same. The invention further relates to a method of operating such a roller leveler.

For flattening high-strength strips and sheets, a high torque is imparted to flatteningrollers to provide for required overstretching necessary for production of planar materials. The permissible torque is limited by the geometry of the flatteningroller journal.

Two-sided driven roller levelers which have, as a rule, a group drive, are generally known. Also known are single drives for flatteningrollers with which the flatteningrollers are driven only on one side.

German Publication DE 1930349A discloses both two-side driving of the strengthening rollers and one-side driving. With this solution, however, the two-sided drive is used only based on space availability when sufficient space is provided for installation of single drives. Because a drive is provided on both sides of the flattening roll, each drive can operate with a half of the power and, thus, can be accommodated in a smaller space.

Korean publication KR 10 1508711B1 discloses a drive roller pair in front or behind the flatteningroller pair in order to apply an additional strip tension to the material. This should limit the required torques.

For flattening high-strength strips and sheets, the entire roller leveler should meet specific requirements to insure the best possible flatness of the material. Thus, for the flattening process, very high torques need to be applied to the flattening rollers. Simultaneously, the flattening roller should be capable to compensate, via an individual control of leveler functions, complex flatness errors.

With one-sided driver flatteningrollers, an imparted high torque can cause an uncontrolled twist between the flatteningroller and the to-be-flattened material which results in uneven flattening that leads to a reduced quality of the flattening. Therefore, the size of the permissible torque is limited by a proper dimensioning of the flattening roller journal.

With two-side driven flattening rollers by a group drive, the torque can be adjusted only together for all of the flattening rollers. Therefore, the torque adjustment or the rotational speed adjustment for setting the roller gap can be done, disadvantageously, also together for all of the flattening rollers. That is why the necessary distribution gears contribute to additional losses and unbalanced distribution.

The arrangement of additional drive rollers for applying a forward or backward pull negatively influences the geometry of a flattening roll, the reason being that thereby the flattening rollers are deflected in the pulling direction. As a result, the roller gap becomes geometrically deformed, worsening the result of the flattening.

Accordingly, the object of the present invention is to so improve the above-described roller leveler and the method of operating the same so that the flattening results are better in comparison with known solutions, and optimal results of flattening can be achieved.

The object of the invention is achieved by each flattening roller having a first rotary drive that can rotate an axial end of the flattening roll, and a second drive that can rotate the opposite end of the flattening roll, and wherein the leveler control is designed to individually control the first and second drives according to set value of a parameter that determines the rotational movement of the flattening roller.

The leveler control can be associated with a set value transmitter that presets the rotational movement parameter for all rotary drives.

The leveler control is preferably designed to apply a predetermined torque to the respective first and second drives. Simultaneously, the leveler control can be designed to impart to the respective first and second drives a predetermined rotational speed.

The leveler control can further be designed to control the parameter that determines the rotational movement of the flattening roller in a closed control cycle. In this case, advantageously, sensors for sensing the torque and/or the rotational speed are provided in the region of the first and second drives, which sensors are connected with the leveler control.

The method of operating such a roller leveler contemplates, according to the invention that each flattening roller has a first rotary drive for rotating one end of the flattening roll, and a second rotary drive that rotates the other, opposite end of the flattening roll, wherein the leveler control is designed to individually control the first and second drives according to a set value of a parameter that determines the rotational movement of the flattening roller.

Advantageously, the leveler control is operable, alternatively, in one of the following modes:

-   -   a) Operating only the first rotary drive of the flattening         rollers;     -   b) Operating only the second rotary drive of the flattening         rollers;     -   c) Operating both the first and second rotary drives of the         flattening rollers.

A set value transmitter can be used for pre-setting a set value of a parameter that controls the rotational movement of the flattening rollers.

The set value transmitter can be associated with a module in which a number of different flattening strategies is stored, wherein for each flattening strategy, a data set for the parameter that determines the rotational movement of the flattening rollers, is available, wherein the module communicates to the set value encoder, the data set according to a selected flattening strategy.

Thus, the invention contemplates that each individual flattening roller is alternatively one-side or two-side driven. Each flattening roller drive can be provided with its own drive control.

Proceeding from the above-described known solution, there is provided a roller leveler as well as a method of operating the same that enables an individual control of each of the flattening rollers and, thus, an individually influenceable flattening process.

By pre-setting the control unit, set value of a drive parameter (torque, rotational speed, number of revolution) can be pre-set. The control unit can be controlled or regulated by the flattening strategy. The flattening strategy can take into account local changes in the flattening gap. A precise adjustment of the drive parameter of each driven flattening roller (torque and/or rotational speed) is also possible, in particular, of the one-side or two-side drive.

Thus, a targeted distribution of the drive parameters on both sides and/or selection of the flattening rollers can take place. Synchronization of the drive parameters and, if needed, a targeted trimming of the drive parameters is also possible.

The proposed solution can further provide for equalization of the load for a targeted torque distribution, whereby an optimal utilization of the service life of the components of the drive train becomes possible. Such load equalization can be based on the following strategy.

It is further very advantageous that during a reverse operation of the roller leveler, completely symmetrical conditions for a preceding flattening pass can be created.

With the proposed method, control of the (active) flattening roller drives can be effected according to the pre-set set values which are predetermined by the flattening strategy of the control unit.

Finally, the flattening process is carried out based on the predetermined or pre-set drive parameters for separate flattening rollers.

If necessary, (with a closed control cycle), a correction of the control of the active flattening roller drives can be effected, i.e., on the bases of the set-actual value comparison of the drive values during the flattening pass.

At that, separate or joint regulation or control of the drives takes place. As mentioned above, a synchronized operation of the drives is also possible. The flattening strategy can take into account the types of the defects of the to-be-flattened material. Also, can be taken into account the wear and tear of the machine (i.e., in particular, tool wear).

When driving the flattening rollers, one is dealing with a contractional unit that consists of an (electrical or hydraulic) drive unit and, if required, associated transmitting gears (including spindles, shafts, couplings, etc.).

In majority of cases the flattening rollers are actively driven. However, it is also possible that for some time flattening rollers are not driven. Therefore, according to the guidelines for flattening strategy, flattening rollers, which are provided therefore, can be actively actuated as long as they actively participate in the deformation process of the material and are required to transmit torque. Nevertheless, individual drives can run idly, without transmitting the torque to the roller; such rollers can be switched off completely, with their drives remaining passive.

The proposed roller leveler as well as the described method are advantageously used for high-strength material when a very high torque of flattening rollers is necessary for the flattening process. They are particularly suitable for flattening high-strength steel sheets and strips.

Advantageously, the present invention permits, due to separate two-side pre-setting and regulation of the torque and/or the rotational speed of the flattening rollers, to individually and timely respond to local defects and flatness errors even with application very high torques.

Therefore, the flattening range of roller levelers can be widened so that the range of products that can be processed with a given configuration of the equipment can also be widen. Thus, in the given case, the need in investment for additional roller levelers is eliminated, while a higher coverage of product range is obtained. Alternatively, the size of a roller leveler for a given task can be reduced.

Further, by one-sided or two-sided change of the torque of one or several flattening rollers, the flattening effect can be purposely adjusted, so that in addition to the known adjustment of the flattening rollers (positioning, bending, pivoting), further effective control means for improving flatness is available.

With reverse operation of a roller leveler, completely symmetrical conditions to the previous flattening pass can be produced.

The drawing shows an embodiment of the invention. Single FIGURE shows a schematic plan view of a roller leveler for flattening a metal strip.

The drawing schematically shows a plan view of a roller leveler 1 having a number of flattening rollers 2 of which only one set is shown. An upper set and a lower set of flattening rollers 2 are provided for flattening a metal strip, not shown. During a flattening process, the strip is advanced in a forward direction F.

Each flattening roller 2 has a drive 3 which, in the present case, consists of first and second drives arranged, respectively at two opposite axial ends of the flattening roller 2. Each flattening roller 2 thus has a drive at each axial end which is, respectively, controlled by leveler control 4. By way of example, this is illustrated for the left side of the roller leveler 1, wherein the first drives L₁, L₂ . . . up to L_(n) are shown. Correspondingly, the second drives R₁, R₂ . . . up to R_(n) are provided at the right side.

The leveler control 4 communicates to the flattening roller 2 their operating parameter via the respective first and second drives. In this way, a separate control applies to both axial ends of the flattening rollers, thus, to both rotary drives. In this way, the right-side control and the left-sight control of all of the flattening rollers 2 take place independently from each other.

This also applies to each separate first and second drives. To this end, the leveler control transmits relevant parameters to the drives, namely, the torque Md with which the rotary drives drive the flattening rollers 2, as well as the number of resolutions (or rotary speed). The pre-set values of the torque or the number of revolutions are retained by the leveler control 4 in a closed control circuit. To this end, sensors 6 are provided (of which only one is shown in the drawing) which determine the actual values (of the torque and the rotary speed) and transmit them to the leveler control 4, so that upon deviation from the set value, readjustment can take place.

By actuation of all of the drives, the leveler control 4 transmits further adjustment parameters to roller leveler in order to adjust the flattening gap and retain it in regulated manner at the predetermined value. This is carried out by setting the immersion depth, deflection, pivoting, the compensation system, etc. Here, however, the case is of per se known method of operation of a roller leveler and, therefore, the above-discussed control is shown in the drawing only schematically by a dash arrow.

In this regard, it should be pointed out the mutual influence of the flattening gap dimensions, material parameters, adjustment parameters, and driving parameters, so that every change is considered not in isolation but as a part of the entire regulation concept.

The leveler control 4 is connected with a set value transmitter 5 in which the concrete data for torque and rotational speed are stored. The leveler control 4, thus, converts set value input data in control data for the leveler functionality. The set value input data contain all necessary parameters and, thus, all driving parameters for adjustment of each flattening roller of the roller leveler and the flattening gap for each flattening pass.

The precise adjustment of the drive parameters (torque, rotational speed of each flattening roller 2 can be expanded by use a one-side drive or a two-side drive, which depends on a pre-determined flattening strategy. To this end, a module 7 for storage or calculation of the flattening strategy is provided and which includes the set value adjuster 5. The selection of a definite flattening strategy, thus, leads to transmitting of corresponding data from module 7 to the set value adjuster 5 and further to the leveler control 4.

In addition, the separate control of the left and right flattening rollers drives Ln,Rn provides for targeted distribution of the driving parameters, so that the drives are synchronized or are controlled or regulated with a desired trimming. In this way, specifically, influence of the flattening on to-be-flattenedproduct can be preset.

It is particularly advantageous to individually control both drives of each flattening roller in order to provide for a load balancing regulation of two adjacent flattening rollers. A targeted regulation of torque distribution has a positive effect on the service life of the drives.

The incorporation of the drive control in the regulation, i.e., adaption of the pre-set torque Md or the rotational speed n is shown on the right side of the drawing. From the drive train, sensor 6 determines the measured variable and transmits it as set/actual value comparison to the leveler control 4 that corrects the controlled deviation. This individual regulation is provided for each right-side and left-side drive. For the sake of clarity, this control circuit is limited to the drive R₁ in the drawing.

The proposed roller leveler 1 may have different concepts and corresponding specific constructional detail for changing the rollers. It makes sense (but not absolutely necessary), to place the drives, at least on one side at which the roller exchange is to-be-taken place, on a common base, in a block, to simplify as much as possible the contemplated process. Exchange of all or separate rollers can be contemplated. In each case, the roller or the entire roller set should be decoupled from their drives, on both sides, and those rollers are removed from the region of the roller leveler.

For roller exchange, the drive of one side (for separate or the totality of rollers) should be removed from the roller exchange zone. To this end, the drive is pushed, dependent on space conditions of the layout of the leveler, in the direction of the roller axis or/and transverse thereto, so that the space in front of the leveler is free for removal the roller set or a separate roller and for inserting into the leveler anew roller or a roller set.

Finally, the drive is brought back in its operational position, the flattening roller are coupled to the drives, and the roller leveler is placed in its ready-for-operation position.

The proposed roller leveler can be used for flattening sheets, strips, and their cut-outs. The thickness of the material varies preferably from 1 mm to 70 mm, particularly advantageous from 1 mm to 30 mm; the maximum material thickness is about 150 mm.

The material width preferably is between 600 mm and 6000 mm, with maximum width about 700 mm.

During processing, the temperature of the material is less than 600° C. The yield strength of the material is preferably above 460 MPa, advantageously above 800 MPa.

LIST OF REFERENCE NUMERALS

-   1 Roller leveler -   2 Flattening roller -   3 Rotary Drive -   4 Leveler Control -   5 Set value transmitter -   6 Sensor -   7 Module for storing flattening strategies -   L₁, L₂ . . . L_(n)) first rotary drive -   R₁, R₂ . . . R_(n)) second rotary drive -   F Forward direction -   Md Torque -   n Rotational speed/number of revolutions 

1. Roller leveler, comprising a set of upper and lower flattening rollers (2), wherein each flattening roller (2) is provided with a rotary drive (3) actuated by leveler control (4) for rotating the flattening roller (2) to advance a to-be-flattened metallic flat material in a forward direction (F) and, thereby, flatten the same, characterized in that each flattening roller (2) has a first rotary drive (L₁, L₂ . . . L_(n)) for driving one axial end of the flattening roller (2), and a second rotary drive (R₁, R₂ . . . R_(n)) for driving another axial end of the flattening roller (2), wherein, the leveler control (4) is designed to control a respective first and second drive (L₁, L₂ . . . L_(n), R₁, R₂ . . . R_(n)) individually to impart thereto, in accordance with a pre-set value, a parameter that determines a rotational movement of the flattening roller (2).
 2. Roller leveler according to claim 1, characterized in that the leveler control (4) is connected with a set value transmitter (5) that transmits parameters of the rotational movement of the flattening rollers (2) to all of the rotary drives (L₁, L₂ . . . L_(n), R₁, R₂ . . . R_(n)).
 3. Roller leveler according to claim 1, characterized in that the leveler control (4) is so formed that a predetermined torque (Md) is imparted to the respective first and second rotary drives (L₁, L₂ . . . L_(n), R₁, R₂ . . . R_(n)).
 4. Roller leveler according to claim 1, characterized in that the leveler control (4/ is so formed that a predetermined rotational speed (n) is imparted to the respective first and second drives (L₁, L₂ . . . L_(n), R₁, R₂ . . . R_(n)).
 5. Roller leveler according to claim 1, characterized in that the leveler control (4) is formed to regulate parameters determining the rotational movement of the flattening rollers (2) in a closed circuit.
 6. Roller leveler according to claim 5, characterized in that the regions of the first and second drives (L₁, L₂ . . . L_(n), R₁, R₂ . . . R_(n)), sensors (6) for detecting of the torque (Md) and/or the rotational speed (n) are provide which communicates with the leveler control (4).
 7. Method of operating a roller leveler having a set of upper and lower flattening rollers (2), wherein each flattening roller (2) is provided with a rotary drive (3) actuated by leveler control (4) for rotating the flattening roller (2) to advance a to-be-flattened metallic flat material in a forward direction (F) and, thereby, flatten the same, characterized in that each flattening roller (2) has a first rotary drive (L₁, L₂ . . . L_(n)) for driving one axial end of the flattening roller (2), and a second rotary drive (R₁, R₂ . . . R_(n)) for driving another axial end of the flattening roller (2), wherein, the leveler control (4) imparts to a respective first and second drive (L₁, L₂ . . . L_(n), R₁, R₂ . . . R_(n)) an individual value for at least one parameter that determines a rotational movement of the flattening roller (2).
 8. Method according to claim 7, characterized in that the leveler control (4) is operated alternatively in one of the following operational mode: a) Operating only the first rotary drive (L₁, L₂ . . . L_(n)) of the flattening roller (2); b) Operating only the second rotary drive (R₁, R₂ . . . R_(n)) of the flattening roller (2); c) Operating both the first rotary drive (L₁, L₂ . . . L_(n)) and the second rotary drive (R₁, R₂ . . . R_(n)) of the flattening roller (2).
 9. Method according to claim 7 or 8, characterized in that a set-value transmitter (5) supplies the leveler control (4) with a pre-set value for a parameter that determines a rotational movement of the flattening roller (2).
 10. Method according to claim 9, characterized in that the set-value transmitter (5) is connected with a module (7) in which a number of different flattening strategies is stored, wherein for each flattening strategy, a data set for the parameter determining rotational movement of the flattening roller (2) is available, and wherein the module (7) communicates, to the set-value transmitter (5), the data set according to a selected flattening strategy. 